Diabetes is a disease that causes high blood sugar levels. Left untreated, high blood sugar levels can cause many problems, such as heart and blood vessel disease, stroke, kidney failure, and blindness. Humulin R and Humalog are two different types of insulin that can help lower your blood sugar level.

These drugs work in slightly different ways. In general, insulin lowers your blood sugar level by signaling to your muscle and fat cells to use sugar from your blood. It also signals your liver to stop making sugar.

Depending on the type and severity of your diabetes, you may need to take insulin. We’ll compare and contrast Humulin R and Humalog to help you decide if one may be a good choice to treat your diabetes.

Humulin R is a brand name for regular insulin. It is a short-acting insulin. That means that it takes about 30 minutes to reach your bloodstream and works for about three to six hours.

Humalog is a brand name for insulin lispro, which is a fast-acting insulin. It takes about 15 minutes to start working, but it only lasts two to four hours. The following table compares more features of these two drugs.

Injectable solution, available in a vial for use with a syringe. Injectable solution, available in a cartridge that you use in a device called a KwikPen

How much do I take?

Your doctor will tell you what dose to inject. This depends on your blood sugar readings and the treatment goals decided by you and your doctor.

Your doctor will tell you what dose to inject. This depends on your blood sugar readings and the treatment goals decided by you and your doctor.

How do I take it?

Inject it subcutaneously (under your skin) into the fat tissue of your abdomen, thighs, buttocks, or upper arm. You can also take this drug through an insulin pump.

Inject it subcutaneously (under your skin) into the fat tissue of your abdomen, thighs, buttocks, or upper arm. You can also take this drug through an insulin pump.

When do I take it?

Within the 30 minutes before a meal

Within the 15 minutes before a meal or right away after eating a meal

Do I take it for long-term or short-term treatment?

Used for long-term treatment

Used for long-term treatment

How do I store it?

Unopened: Store unopened insulin in a refrigerator at a temperature between 36°F and 46°F (2°C and 8°C). Opened: Store opened Humulin R below 86°F (30°C). Throw it away after 31 days.

Unopened: Store unopened insulin in a refrigerator at a temperature between 36°F and 46°F (2°C and 8°C). Opened: Store an opened Humalog vial or KwikPen at room temperature below 86°F (30°C). Throw it away after 28 days.

Humulin R is usually less expensive than Humalog. Your local pharmacy should be able to give you exact costs. Most pharmacies carry both of these medications. It’s likely that your insurance plan also covers both Humalog and Humulin R, but you should check with your insurance company before your doctor prescribes either drug.

Humalog and Humulin R have similar interactions with other substances. An interaction is what happens when you take a drug with another substance or drug. Sometimes interactions are harmful or affect how a drug works. It is important to tell your doctor about all medications, vitamins, or herbs you’re taking to help avoid harmful interactions.

Interactions that cause low blood sugar

Humalog and Humulin R may cause your blood sugar level to get too low if you take them with any of the following drugs:

other diabetes drugs

fluoxetine, a drug used to treat depression

beta-blockers used to treat high blood pressure such as:

metoprolol

propranolol

labetalol

nadolol

atenolol

acebutolol

sotalol

sulfonamide antibiotics such as sulfamethoxazole

Note: Beta-blockers and other drugs used to treat high blood pressure, such as clonidine, may also make it difficult to recognize the symptoms of low blood sugar.

Interactions that decrease effectiveness

Humalog and Humulin may not work as well if you take them with any of the following drugs:

People with kidney problems or liver problemsmay be at increased risk for low blood sugar while using Humalog or Humulin R. If you have these problems, you may need to monitor your blood sugar more often.

It is especially important for you to keep your blood sugar levels in a healthy range while you’re pregnant. High blood sugar levels during pregnancy can lead to complications, such as high blood pressure and birth defects.

BothHumalog and Humulin R are considered safer drugs to control high blood sugar during pregnancy. They are both forms of insulin, and insulin is the preferred treatment for pregnant women with diabetes.

Breastfeeding while taking either of these two types of insulin is generally considered safe. Some insulin can pass through breast milk to the child, though. Talk to your doctor if you want to breastfeed while taking Humalog or Humulin R. Your doctor will most likely adjust your dosage.

Humalog and Humulin R have similar results when either drug is injected under the skin. When either drug is used in an insulin pump, though, Humalog may be slightly more effective at controlling blood sugar than Humulin R is.

Humalog starts working faster than Humulin R after an injection. It’s most effective 30–90 minutes after you inject it. Humulin R, on the other hand, is most effective three hours after you inject it. Humulin R takes longer to work, but its effects also last longer than Humalog’s.

Both Humalog and Humulin R are safe and effective at controlling high blood sugar levels in certain people with diabetes. Talk to your doctor about these drugs. You might want to ask them the following questions:

Is one of these drugs right for treating my diabetes?

What’s the best way to give myself the drug?

How do I give myself an injection?

How do I dispose of used needles and sharps properly?

How do I use an infusion pump to give myself the drug?

How should I care for the pump?

Does this drug interact with my other medications?

Your doctor can help decide if this drug is a good option to control your diabetes and answer any other questions you may have.

Medically reviewed by Alan Carter on May 19, 2016 — Written by University of Illinois-Chicago, Drug Information Group